一株耐热脂肪酶产生菌的筛选及酶学性质研究

从云南省富油地采取了60份土样中,利用透明圈法筛选出一株耐热脂肪酶产生菌。对其酶学性质和发酵条件进行了研究,酶学性质表明,该酶最适作用温度为50℃,最适pH6.0,在pH3.0-8.0范围内稳定,在60℃保温60 min酶活还保留70%;70℃保温60 min残余50%;具有良好的热稳定性;不同金属离子有不同的作用,Ca+,K+对酶有激活作用,Fe3+、Pb2+、Mn2、Cu2+、Al3+、Zn2+对酶活有抑制作用。EDTA对酶影响不大。产酶最佳条件为:MgSO4.7H2O 0.05 g,K2HPO40.1 g,CaCO30.25 g,可溶性淀粉2.5 g,大豆粉2.5 g,装液量50 mL。这株细菌通过培养基优化酶活达到20.3 U/mL。

The Screening of Thermostable Lipase-producing Bacterium and Study on Properties of Lipase

From 60 oil-rich soil samples in Yunnan province,a thermostable lipase-producing bacterium was screened by using a transparent circle method.The nature of its enzymatic and fermentation conditions was studied.Enzymatic properties showed that the enzyme optimal temperature is 50℃,optimum pH6.0,the lipase activity is stable at pH3.0-8.0,and enzymatic activity retained 70%at 60%for 60 minutes.The residual is 50%at 70℃ for 60 minutes.Different metal ions showed diverse effects on the lipase activities,Ca~+,K~+ increased lipase activities,whereas Fe~(3+),Pb~(2+),Mn~(2+),Cu~(2+),Al~(3+),Zn~(2+)can inhibit the enzyme activity.EDTA effect on the enzyme little bit.Optimum conditions for enzyme production:MgSO_47H_2O 0.05 g,K_2HPO_4 0.1 g,CaCO_30.25 g,soluble starch 2.5 g,soybean powder 2.5 g,liquid volume 50 mL.This strain of bacteria of enzymatic activity can achieve 20.3 U/ml through the medium optimization.